The present invention relates to a measuring apparatus for biological information to carry out noninvasive determination of biological information such as pulse rate and blood sugar level.
A number of measuring apparatuses for biological information have been proposed. For example, Japanese Laid-Open Patent Publication No. Hei 8-66378 has disclosed a pulsimeter for measuring a pulse rate on the basis of a change in intensity of light passed through an earlobe. A measuring terminal disclosed in the publication is outlined in FIG. 5.
As shown, the measuring terminal includes a pair of gripping pieces 22 and 24 which are jointed by a jointing elements 25 and pressed against each other by a spring 26. The gripping pieces 22 and 24 are provided with contact pads 27 and 28, respectively. Further, a light emitting element 21 and a light receiving element 23 are arranged on the gripping piece 22 and 24, respectively, so as to face each other. In taking a measurement, the measuring terminal of the pulsimeter is placed on the earlobe with the two gripping pieces 22 and 24 holding the earlobe therebetween, and a light is emitted from the light emitting element 21. The light receiving element 23 detects the light projected by the light emitting element 21 and passed through the earlobe.
A blood flow is not uniform but pulsates. Besides, a light transmittance through blood is lower than that through other substances forming a living body such as, for example, the skin. Therefore, an intensity of the light passed through the earlobe changes in rhythm with the pulse. The prior art pulsimeter calculates the pulse rate on the basis of the change in the intensity of light passed through the earlobe. Measurement of the pulse rate can be taken on other parts than the earlobe. For accurate determination, the light emitting element 21 and the light receiving element 23 are located apart from the contact pads 27 and 28, respectively.
However, such a pulsimeter presents the following problems.
The measuring terminal of the pulsimeter is pressed against the earlobe and left hanging therefrom during the measurement. When measurement is taken with a moving subject as in measurement of the pulse rate of a person in motion, the measuring terminal swings, thereby causing an increase in load on the earlobe hanging the measuring terminal. That makes it difficult to take an accurate measurement, and also causes a feeling of physical disorder and discomfort for the subject. A long measurement session, in particular, could turn such feeling of physical disorder and discomfort to mental pain.
Thus, it is an object of the present invention to provide a measuring apparatus for taking a biological information which can solve those problems and permits accurate measurements for taking biological information without causing the subject much discomfort or the like.